EUCRATIDES, king of Bactria (c. 175-129 B.c.), came to the throne by a rebellion against the dynasty of Euthydemus, whose son Demetrius had conquered western India. His authority was challenged by a great many other pretenders and Greek dynasts in Sogdiana, Aria (Herat), Drangiana (Sijistan), etc., including Pantaleon, Agathocles, Antimachus, Antalcidas "the victorious" (vuc''4opos), and Plato, whose unique coin is dated from the year 147 of the Seleucid era ( =166 B.c.). In the west the Parthian king Mithradates I. attacked Eucratides; he suc ceeded in conquering two provinces between Bactria and Parthia. But the principal opponent of Eucratides was Demetrius (q.v.) of India, who attacked him with a large army "of 300,00o men"; Eucratides fled with 30o men into a fortress and was besieged. But at last he beat Demetrius, and conquered a great part of western India. According to Apollodorus of Artemita, the his torian of the Parthians, he ruled over ',coo towns (Strabo xv. 686; transferred to Diodotus of Bactria in Justin 41, 4. 6) ; and the extent of his kingdom over Bactria, Sogdiana (Bokhara), Drangiana (Sijistan), Kabul and the western Punjab is confirmed by numerous coins, he is called "the great King Eucratides." On one his portrait and name are associated on the reverse with those of Heliocles and Laodice; Heliocles was probably his son, and the coin may have been struck to celebrate his marriage with Laodice, who seems to have been a Seleucid princess.
In Bactria Eucratides founded a Greek city, Eucratideia (Strabo xi. 516, Ptolem. vi. 11. 8). On his return from India Eucratides was (c. 15o B.c.) murdered by his son, whom he had made co-regent (Justin 41, 6). This son is probably the Heliocles just mentioned, who on his coins calls himself "the Just" ((3avc MMws `IlXto,cXiovs &Kalov). In his time the Graeco-Bactrian kingdom lost the countries north of the Hindu Kush. Mongolian tribes, the Yue-chi of the Chinese, called by the Greeks Scythians, by the Indians Saka, among which the Tochari are the most con spicuous, invaded Sogdiana in 159 B.C. and conquered Bactria in 139. Meanwhile the Parthian kings Mithradates I. and Phraates II. conquered the provinces in the west of the Hindu Kush (Justin 41, 6. 8); for a short time Mithradates I. extended his dominion to the borders of India (Diod. 33. 18, Orosius v. 4. 16). When Antiochus VII. Sidetes tried once more to restore the Seleucid dominion in 130, Phraates allied himself with the Scythians (Justin 42, I. I) ; but after his decisive victory in 129 he was attacked by them and fell in the battle. The changed state of affairs is shown by the fact that on his later coins Heliocles passes over to a native silver standard, and his bronze coins became quite barbarous. These and the coins of many other Greek kings of these times are records of a desperate struggle of the Greeks to maintain their nationality and independence in the Far East, which accelerated their destruction; about 120 B.C. almost the whole of eastern Iran was in the hands either of a Parthian dynasty or of the Mongol invaders, who are now called Indo Scythians. Only in the Kabul valley and western India the Greeks maintained themselves about two generations longer (see MENANDER). (ED. M.)